Guard cell abscisic acid signalling and engineering drought hardiness in plants

Guard cells are located in the epidermis of plant leaves, and in pairs surr ound stomatal pores. These control both the influx of CO2 as a raw material for photosynthesis and water loss from plants through transpiration to the atmosphere. Guard cells have become a highly developed system for dissecti ng early signal transduction mechanisms in plants. In response to drought, plants synthesize the hormone abscisic acid, which triggers closing of stom ata, thus reducing water loss. Recently, central regulators of guard cell a bscisic acid signalling have been discovered. The molecular understanding o f the guard cell signal transduction network opens possibilities for engine ering stomatal responses to control CO2 intake and plant water loss.